Researchers at Stanford University, who conducted the largest study to date of African-Americans’ genetics and smoking behavior, have found a genetic marker that influences smoking habits. The marker is correlated with how many cigarettes per day a person smokes.

The researchers studied a gene that has been found in previous studies to predict smoking behavior in people of European descent. The specific genetic marker within that gene that they focused on varies in people of different ethnicities, Health Canal reports. The study included data from more than 32,000 African Americans.

“Knowing that this gene is important in different ancestral groups really points to its importance and suggests it as a target for drug discovery and development,” lead researcher Sean David, MD said in a news release. He noted that African Americans tend to take up smoking at a later age than those of European descent, and smoke fewer cigarettes daily. They have a higher risk of developing lung cancer, however. They are also less likely to quit smoking.

The results appear in the journal Translational Psychiatry.

A  study published by the Centers for Disease Control and Prevention (CDC) in November 2011 found almost 76 percent of African-American smokers wanted to quit in 2010. While 59 percent tried, only 3 percent were successful, the lowest rate among races and ethnicities measured by the CDC.